(HealthDay News) – Patients with type 2 diabetes with either a short or long sleep duration have significantly higher hemoglobin A1c (A1C) levels compared to patients with intermediate sleep duration, according to research published in the March issue of Diabetes Care.

Toshiaki Ohkuma, MD, of the Kyushu University in Fukuoka, Japan, and colleagues analyzed data from 4,870 Japanese patients with type 2 diabetes who participated in the Fukuoka Diabetes Registry.

According to the researchers, subjects with short (<4.5 hours) or long (>8.5 hours) sleep duration had higher A1C levels compared with subjects sleeping for 6.5–7.4 hours, indicating a U-shaped association. The association of sleep duration with obesity and A1C levels was observed to be U-shaped even after adjustments for various confounding variables.

“In conclusion, the current study is the first epidemiological study to demonstrate the U-shaped associations of sleep duration with obesity and glycemic level in patients with type 2 diabetes,” the authors write. “Our findings suggest that patients with either a short or long sleep duration should be considered high-risk patients for poor glycemic control, and this may have important implications for the clinical management of diabetes.”

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